Method of making a flexible corrugated wall



Aug. 23, 1949. F. w. GEHRER 2,479,577

I METHOD OF MAKING A FLEXIBLE CORRUGATED WALL Filed March 12, 1945 3 Sheets-Sheet l L L W L 3/ INVENTOR.

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Aug. 23, 1149.

F. W. GEHRER METHOD OF MAKING A FLEXIBLE CORRUGATED WALL 3 Sheets-Sheet 2 Filed March 12, 1945 I N VEN TOR.

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9 4 v (a Z 6 I L. Q3 F 1 r W 2 F. W. GEHRER METHOD OF MAKING A FLEXIBLE CORRUGATED WALL 3 Sheets-Sheet 3 Filed March 12, 1945 INVENTOR.

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WW/ W p 2% W a it 2 Patented Aug. 23, 1949 METHOD OF MAKING A FLEXIBLE CORRUGATED WALL Frederick W. Gehrer, Chicago, 111., assignor to Cook Electric Company, Chicago, 111., a. corporation of Illinois Application March 12, 1945, Serial No. 532,391

Claims. 1

.Ihis invention relates to a method. of making corrugated metal walls.

Various methods of making corrugated walls have been suggested, but they involve extending the corrugations outwardly of the tubular blank. The corrugations are therefore of greater diameter than the diameter of the tubular blank and the metal is stretched. Due to the procedure followed, these methods generally limit the thickness of the metal and the depth of the corruga-' tion to be formed, and they impose limitations as to size and characteristics of the finished product and the use to which it may be put.

An object of the invention is to provide a new and novel method of making a seamless corrugated tubular wall. The corrugations are formed inwardly of the tubular blank so 'as to be of less diameter than the diameter of the tubular blank. The operation is preferably one of folding the metal with minimum, if any, stretching, the metal being flowed by a more or less rolling or ironing action to compensate for the corrugations being of smaller diameter than the stock so as to avoid wrinkling or other undesirable disturbance of the metal and to produce a relatively uniform thickness to' the wall of the finished product.

In its more specific aspects, the method includes spinning the metal by varying increments. The steps employed result preferably in a flow of the metal producing corrugations of desired depth Without disturbing the metal.

In one of the variant embodiments of the invention, the method includes forming the metal into a plurality of corrugations of limited depth, but preferably with the inner portion thereof, which may include one or more inner corrugations, of greater depth than the outer portions, so that the metal of this inner portion will be formed to a greater degree at the beginning, and then the metal of the outer portions further formed, the steps including bringing all the corrugations by increments to the desired final depth without injury to the metal.

If so desired, the method may novelly include the feature of spinning the metal into a plurality of corrugations in groups substantially in continuous relation, with the inner portions of each group spun to a greater depth at the start in order initially to efiect slightly greater spinning of the metal of these inner portions. The metal atlthe outer portions will not be thereby disturbed. The next step may then involve spinning the metal of the outer portions to the same or a different degree. Finally, all the corrugations may then be broughtto the desired final depth.

I have found that-the outer or end corrugation of one group may be utilized as a guide or anchormg means for the rollers in drawing successive groups, and hence, the metal of the outer corru gation or corrugations of each group may be held from being initially formed as much as the metal of the inner portion. Thus, the flow of the metal can be controlled, so that, when thicker metals are used, there is little, if any, danger of unevenness in the final product disturbing the grain structure or causing fracturing or cracking of the metal.

Other objects of the invention will be apparent from the following detail description when taken in connection with the accompanying drawings.

In the drawings:

Figure 1 illustrates in side view one form of the invention disclosed;

Fig. 2 is a vertical sectional view or the same;

Fig; 3 illustrates the starting blank from which the corrugated tubular wall is formed;

Fig. 4 illustrates the second step in forming the finished blank;

Fig. 5 illustrates the next step which involves spinning the circular blank into the cylindrical form shown;

Fig; 6 illustrates the bottom of this pan cut away to leave the finished seamless tubular blank for corrugating;

Fig. '7 illustrates the machine employing the rollers elfecting the corrugating operations;

Fig. 8 illustrates the first step of the corrugating, which draws a plurality of corrugations of limited depth with the middle corrugation more deeply drawn;

Fig. 9 illustrates the product after the first step;

Fig. 10 illustrates the second step;

Fig. 11 illustrates the product after the second step;

Fig. 12 illustrates the third step;

Fig. 13 illustrates the product after the third step:

Fig. '14 illustrates the fourth step;

Fig. 15 illustrates the product after the fourth step;

Figs. 16 and 1'7 illustrate the fifth step; and

Fig. 18 illustrates the final step of sizing to efie'ct uniformity and straightening of the corrugations.

A corrugated tubular wall I formed by the process disclosed herein is illustrated in Figs. 1 and 2. It may comprise any number of cormgations 2 of any desirable depth, but formed relatlvely deep when desired, end flanges 3 and 4 being provided for attachment of end fittings or end plates which form a part of the expansible and contractible vessel when the corrugated tubular wall is used as such, it being understood that the corrugated tubular wall may be used wherever desired, and that it is contemplated at the outset that the inventiondisclosed herein will produce certain novel advantages in certain installations when end flanges are included and. 1

the other novel advantages will beobtained when the end flanges are not included. The depth of the corrugations 2 appear relatively small in Figs. 1 and 2, but the diameters ofthe structures Y shown are substantial, which causes the depth of the corrugations to appear small.

The process disclosed herein has permitted forming metal from .015 to .040 thick into corrugated tubular walls, shown in Figs. 1 and 2,-'of

more than fifteen inches. in diameter with corrugations more thanone-half inchdeep. The forming operations will preferably reduce the thickness of the metal at the corrugations, but it will be substantially uniform without injury to the metal. I have found for example that stock of .032 inch will in certain instancesbe reduced to .025 inch at the walls of the corrugations and .020 at the bends of the corrugations. These figures will vary, butthey illustratethat thick metal may be spun to form relatively deep cor rugations and corrugated tubular walls of substantial size may be made. They also may be made stronger and have many new uses.

To make the tubular wall seamless, a piece of sheet metal shown in Fig. 3 is cut to form the circular piece 5. Piece 5 may then be spun to form a shallow pan 6, which, with the bottom I cut therefrom, as shown in Fig. ,6, will form the tubular wall 8 to be corrugated. Bottom 'I may then comprise the circular piece 5 shown in Fig. 4 of a small size unit to be corrugated. Wall 8 is thus uniquely made without a seam, although it may be of considerable diameter and not a small tube of pipe-like dimensions. It will be roller II will enter grooves of the upper roller I0. Bead [6 being greater in depth than beads I! will enter the middle groove l8 of the lower roller II the entire depth and fold the metal to a greater extent at this middle portion than at the outer portions. This folding action is equally distributed throughout the middle portion, and consequently, the metal is not strained to disturb the grain structure to the point of fracturing or cracking the metal.

When thicker metals are employed and it is desirable to form corrugations of substantial depth, minimum folding during any one operation is desirable within practical limits of operating costs. Consequently, forming a minimum number of corrugations on the first operation may produce better results, although forming more than three corrugations, as shown in Fig. 8,

understood, however, that the forming steps to be hereinafter described might be applied to corrugating small; tubes of pipe-like dimensions without departing from novelty residing in employing such forming steps.

In order to spin wall 8 in small increments and by a number ofoperations, with the middle portion initially, spun .more than the outer portions, I. provide a pair of rollers H1 and l l adapted to be mounted upon rotatably driven spindles l2 and I3 adjustable toward and away from each other, say by device I4, and-axially of each other by devices like l5. Roller I0 may be the upper roller and roller ll may be the lower roller. Upper roller I0 is preferably the male die and lower roller l l is the female die, the former having a series of annular ribs or beads, the inner being designated I6 and-the outer being designated H, which may beof smaller diameter than the inner. Lower rollerll may have a series of grooves [8 of equal ;depth to receive beads I6 and H, the number of each depending upon the number of corrugations to be formed upon each operation. Y r V V It will be observed that grooves l8 are of greater depth than beads H, but'of the same depth as bead l6. Upon the first spinning operation, tubular wallB' is placed upon lower roller l I and upper roller I0 is brought against the work through operation of device l4. Beads I! of the upper roller I0 will enter outergrooves I8 of the lower roller 1 I, while beads 19 of the lower may be preferred. In any event, folding the metalto a greater degree at the middle portion may be employed when it can be accomplished without injury to the metal.

The action of rollers Ill and H upon the metal is principally one of folding. Stretching may be eliminated if it is possible, although some stretching may occur without experiencing detrimental efiects of a serious character. The seamless cylindrical wall '8 is placed upon roller H and beads l6 and I! are brought downwardly thereupon so that the metal is folded inwardly with respect to the diameter of the cylindrical wall. I find that folding the outer portions to a lesser depth than the middle portionwill allow the two outer folds 22 and 23 and the inner fold 24 to be formed without excess material piling up or wrinkling of the material. Inward folding of the metal eliminates the need of stretchingbecause the material at the folds assumes a smaller diameter.

The product formed by the first operation is shown in Fig. 9. It includes the two outwardly formed folds or corrugations 25 and 2B, the inwardly formed folds or corrugations 22, 23 and 24, and the unworkedends 21 and 28. This product is then lifted'from lower roller II and repositioned thereupon to place corrugations 23 opposite the left hand outer groove H3 in roller ll whence it is seated with a fresh portion of the wall 8 of end 28 over the middleand the right hand grooves l8. Placing corrugation 23 in the left hand groove I8 anchors the work so that during the next operation when roller I0 is brought against roller II, as shown in Fig. 10, another group or series of folds or corrugations 29 to 32 will be formed, the product of this second operation being shown in Fig. 11'. Corrugations 29 and 30 are inwardly turned while corrugations 3| and 32 are outwardly turned. Again the corrugation or'corrugations representing the middle portion of this group or series is formed deeper than those of the outer portion. If a single corrugation like corrugation 29 comprises the inner portion, it will be folded deeper than corrugations 23 and 30.

When this second operation is completed, the product thus formed will have inwardly turned corrugations of alternating depths, the corrugations 24 and 29 being of greater depth than the corrugations 22, 23 and 3B, the latter representing the outer portions of the two operations. At this point, it will be understood, however, that both the inner and outer portions may comprise more than a single corrugation if so desired.

The next step comprises deepening corrugation 23 to the same depth as corrugations 24 and 29. This operation is shown inFig. 12. The lower roller II is removed from spindle I3 and another roller 35 is substituted. Roller 35 is substantially the same as roller II except for the provision of four grooves 36 instead of the three grooves l8. Grooves 36 are preferably of the same depth as grooves I8. Corrugations 24, 23, 29 and 30 are seated in these grooves and upper roller I0 is pos'itioned so as to bring deeper head 16 into corrugation 23 to deepen the same to the same depth as the other two middle corrugations 24 and 29. Due to the surplus material gathering at these corrugations when formed inwardly of the wall Bso that they have a diameter smaller than the wall 8, the action of bead I6 is more or less that of rolling or ironing out the metal without stretching the same. Beads ll entering corrugations 24 and 29 act to anchor the product during the deepening of corrugations 23.

The next step involves deepening outer corrugations 22 and 32 to the same depth as the other corrugations 24, 23 and 29, and, at the same time, further deepening all these corrugations, the amount of deepening depending upon the metal and its thickness to avoid disturbing grain structure or any injury that is apt to cause cracking or fracturing. This step may be uniquely accomplished by rollers 38 and 39 shown in Fig.

14. The operation involves first giving the corrugations a substantially V-shape cross section and extending their depth slightly. Roller 39 is provided with a groove 40 for each inwardly formed corrugation. The grooves 40 are separated by ribs 4 l' adapted to receive the outwardly formed corrugations 25, 2G, 31 and 32. Upper roller 38 is provided with ribs 42 whichare less in thickness than the width of inwardly formed corrugations 22, "4, 23, 29 and 30. As will be noted in Fig. 14, ribs 42 will narrow these corrugations at the curved ends and cause them to assume a. somewhat V formation.

The product is then removed and subjected to a further operation illustrated in Figs. 16 and 17. A roller 43 provided with a rib 44 is brought against the product upon a roller 45' having two ribs 46 spaced by a groove 41 of substantially the same width as grooves 40 of roller 39. Rib 44 is thicker than ribs 42 of roller 38. This thickness may bear a predetermined relation to'the width of groove 41, so that, as roller 43 is brought toward roller 45, rib 44 will force the inwardly formed corrugation into groove 41 and restore it to its former shape as shown in Fig. 17. Each inwardly formed corrugation is treated as shown. Not only is the shape restored, but the depth is increased, which may be the final operation for producing the desired depth. The action upon the metal is largely rolling or ironing of the metal without stretching, although there may be a slight stretching at this point if so desired. The metal is caused to flow principally by this rolling action. The thickness of the metal will remain somewhat uniform although there may be .a slight reduction at certain locations. For example, if stock of .032 inch thickness is used, it will be found that the thickness maybe reduced to .020 inch at the curved portions of the inwardly formed corrugations and to .025 inch at the curved por-v tions of the outwardly formed corrugations. The ends 2'! and 28 after being spun into end flanges 3 and 4, if the same are to be provided, will have their wall thickness reduced to about'.027 inch, this depending upon the extent of the operation to form these end flanges. These figures are merely illustrative and may be varied according to the extent of the rolling action of the metal to produce the desired depth of corrugations, the

kind of metal used and the thickness thereof.

To assure uniformity of the corrugations and their alignment with each other, the product may be placed upon a smooth surfaced rotating cylinder 52 and a rotating sizing roller 53 may then be brought toward the same so that beads or ribs 54 of roller 53 will enter the inwardly formed corrugations 22, 23, 24, 29 and 30, as shown in Fig. 18. The corrugations are then pressed against cylinder 52 to straighten the corrugations and to produce said uniformity.

It will be understood that the metal may be annealed after any of the operations shown in Figs. 8, 10, 12, 14 and 16 if it is deemed necessary.

To illustrate the advantages to be obtained by the invention disclosed, one example of the product that may be produced has been specifically set out by way of dimensions in the drawings. In the initial folding operation shown in Fig. 8, grooves l8 may be for instance of a depth of inch, and the middle bead IE of roller 19 of the same size. However, outer beads I! may be 3% inch in depth so that the outside folds will not be as deep as the middle fold. Hence, the folding action will be slightly greater at the middle portion. The same action takes place in the formation of corrugations 29 and 30 as shown in Fig. 10, corrugation 29 being the middle fold and deeper by W inch than the outside folds 22 and 30. After the step shown in Fig. 10 is completed, corrugation 23 becomes a portion of the middle portion and its depth is then increased 26, inch by the step illustrated in Fig. 12. In other words, at this stage of the method, the middle corrugations have been folded deeper than the outside corrugations. It will be apparent that any number of steps like those illustrated in Figs. 8, 10 and 12 may be employed so that more than two series or groups of corrugations may be incorporated in the final product. Even a single series may be used. It is not necessary that only three folds be formed in the first folding operation and thereafter two adopted for the second or succeeding operation. This number may also be obviously changed.

The depth of the corrugations is then extended to /32 inch by the step shown in Fig. 14 and to /32 inch by the step shown in Figs. 16 and 1'7. Thus, the corrugations are formed by small in crements and in a manner to prevent injury to the grain of the metal. The metal is rolled or compressed to prevent being placed under tension. As stated previously, there may be slight stretching of the metal present, but it is preferably held at a minimum. This reference to dimensions is not to be construed as a limitation upon the scope of the disclosure, but only as illustrative of the invention and how the metal may be gradually shaped into corrugations without injury thereto.

From the foregoing explanation, it will be apparent that certain of the steps may be used independently of the others, although the invention is directly primary to producing a product having the characteristics that will be obtained when the process in its entirety is used. For example, forming the seamless wall 8 in the manner disclosed is novel and useful. 0n the other hand, forming a corrugated tubular wall by the steps of Figs. 8, 10 and 12 is also novel, and it is quite obvious that outer corrugations 22 and 30 may be deepened to the same depth as inner corrugations 23, 24 and 29 without anyfurtherdeepening operation of all the corrugations.-

The product produced is exceptionally novel. It may be made in larger diameters and of greater corrugation depth than heretofore. Also, heavier metals may be used to exceptional ad-- vantage. The uses of the product are greatly extended.

Without further elaboration, the foregoing. will so fully explain the gist of my invention that others may, by applying current knowledge, readily adapt the same for use under varying conditions of service, without eliminating certainfeatures, which may properly be said to constitute the essential items of novelty involved, which items are intended to be defined and secured to me by the following claims.

I claim:

1. The method of making a flexible corrugated metal wall which includes forming in one operation a relatively thin tubular wall into a plurality but not all of the corrugations to be formed to a depth less than a final depth, repeating the forming operation to form the remaining corrugations likewise of less depth than a final depth, certain of the intermediate corrugations being formed deeper than the outer corrugations, subjecting said corrugations to afurther forming operation to deepen the same and to provide uniform depth to all, then forming the corrugations to their final depth, and sizing the corrugations to make the same relatively uniform.

2. In the manufacture of a corrugated metal tubular wall of relatively large diameter, the method of forming the metal wall into a series of corrugations which comprises forming certain of the inner corrugations more deeply than the others but not to a final depth, then forming all the corrugations to a greater but even depth, and then forming the corrugations to a still greater depth.

3. In the manufacture of a corrugated metal tubular wall, the method of forming the metal into a plurality of corrugations by first forming one group of corrugations having its outer corrugations initially formed less deep than the middle, and then forming another group of corrugations contiguous with the first group, the form'- ing operation efiecting a deeper drawing of the metal of the middle portion of the second group of corrugations than its outer end portion, then forming all the corrugations to effect a greater depth for the same, and finally, forming all the corrugations to their final depth.

4. In the manufacture of a corrugated metal tubular WalLthe method of forming the metal into a plurality of corrugations by first forming one group of corrugations and then another group in continuous relation therewith, the middle portion of each group being formed to a greater depth than the outer corrugations of each group, effecting a further forming operation to secure uniform depth for all middle corrugations, effecting a further forming operation to deepen the outer corrugations to substantially the same depth as the middle corrugations, and then effecting a further forming operation of all corrugations to a still greater depth. f

5. In the manufacture of a corrugated metal tubular wall, the method of forming the metal into a plurality of corrugations by first forming one group of corrugations and then another group substantially in continuous relation therewith, the .middle portion of each group bein formed to agreater depth than the outer corrugations tion to secure substantially the same depth for the outer corrugations as for said middle ortion, and finally drawing all the corrugations to a greater depth.

-6. In the manufacture of a corrugated metal tubular Wall, the method of forming the metal into a plurality .of corrugations by forming the corrugations in groups in substantially continu ous relation with each other, the middle portion of each group being initially formed to a greater depth than the outer portion of each group, then effecting a forming of the metal to secure substantially uniform depth of all corrugations, and finally, forming .all corrugations to a still greater depth without fracturing or cracking the metal.

7. In the manufacture of a corrugated metal tubular wall of a relatively large diameter, the method of forming the metal into a plurality of corrugations by forming the corrugations in groups substantially in continuous relation with each other, the middle portion of each group being initially formed to a greater depth than the outer portion of each group, then effecting a formingof the metal to secure substantially uniform depth of all corrugations, and effecting suc. cessive forming operations to deepen said corrugations still further without fracturing or cracking the metal or weakening the same at the bends of the corrugations.

8. In the manufacture of a corrugated metal tubular wall, the method of forming the metal into a plurality of corrugation in groups substantially in continuous relation with each other by a plurality of die rollers each having a number of annular ribs of predetermined depth, initially utilizing at least two of said rollers to form said groups of corrugations in continuous rela-. tion by a successive forming operation for each successive group, utilizing the end corrugation of one group as a guide and anchoring means for the rollers in making a successive forming operation, thereafter deepening the corrugations by rollers having ribs of greater depth, and continuing such use of roller having ribs of greater depth until the metal of the corrugations is formed to a final depth without fracturing o cracking the same.

9. In the manufacture of a corrugated metal tubular wall, the method of forming the metal into a. plurality of corrugations in groups sub-. stantially in continuous relation with each other by a plurality of dierollers each having a number of annular ribs of predetermined depth, initially utilizing at least two of said rollers to form said groups of corrugations in continuous relation by a successive forming operation for each successive group, utilizing the end corrugation of one group as a guide and anchoring means for the rollers in making a successive forming operation; the ribs at the middle portions of said rollers being-of greater'depth than the outer ribs there'- of to effect a greater forming initially of the metal bythe ribs at said middle portions, then forming the end corrugation of any group used as a guide and anchor to a depth equal to the ribs of said middle portions, also forming the outer ribs to a like depth, and thereafter effecting further forming of the metal of all the ribs to produce the final depth desired.

10. In the manufacture of a corrugated metal tubular wall, the method of formin the metal into a plurality of corrugations in group substantially in continuous relation with each other by a plurality of die rollerseach having a number of annular ribs of predetermined depth, initially utilizing at least two of said rollers to form said groups of corrugations in continuous relation by a successive forming operation for each successive group, utilizing the end corrugations of one group as a guide and anchoring means for the rollers in making a successive forming operation for another group, the ribs at the middle portions of said rollers being of greater depth than the outer ribs thereof to eifect a greater forming initially of the metal by the ribs at said middle portions, then forming the end corrugation of any group used as a guide and anchor to a depth equal to the ribs of said middle portions, also forming the outer ribs to a like depth, and thereafter effecting further forming of the metal of all the ribs to produce the final depth desired whereby the metal is drawn to a substantially uniform thickness without fracturing or cracking the same, and finally straightening the corrugations by a rolling operation.

FREDERICK W. GEHRER.

REFERENCES CITED The -following references are of record in the file of this patent:

UNITED STATES PATENTS 

